This invention relates to a method and an apparatus for loading/unloading a drum member relative to a frame in which the drum member is used.
In an electro-photographic printing apparatus or an electro-photographic copier, an electro-static latent image forming drum coated with photosensitive material is provided. In such apparatus, many associated devices such as a corona charger, a developer, pre-cleaning decharger, etc. are arranged close to the drum. Therefore, when the drum is to be loaded into or unloaded from the frame for inspections or replacement, very careful handling is required, or else the drum will be damaged by hitting these devices.
Damage to the drum is also likely in a magnetic drum memory apparatus or any other apparatus including a sensitive drum member provided with associated devices in its vicinity.
The drum member is usually supported by a center shaft, which is secured at one end to the frame of the apparatus. The other end of the center shaft is free or easily detachably fixed to the frame.
A conventional method of loading/unloading the drum includes the steps of connecting a separate tool such as an extension rod to the free end of the center shaft for elongating or extending the center shaft, and drawing out the drum while guiding the drum along the extension rod.
Another prior art method, as shown in Japanese laid-opened patent application Tokkaisho No. 60-15942, includes the steps of providing a center shaft made as a pipe, providing a special rod having a length longer than the length of the drum, inserting the rod into the center shaft pipe, securing one end of the rod to the frame, detaching the center shaft, and then drawing out both the drum and center shaft together.
In either prior art method, a special tool, such as the extension rd, must be provided and also a space for housing this tool must be provided in the frame. Therefore, the size of the frame becomes undesirably larger.
Furthermore, a maintenance person is required to expend much labor to attach and detach the tool every time the drum is loaded/unloaded. PG,3
In addition, such electro-photographic apparatus is generally provided with an electric power switch which cooperates with the opening/closing of a front door thereof so that the power supply is cut when the door is opened. In the case where the tool is housed within the frame, and a maintenance person forgets to store the tool in the frame, the front door must be opened once again, and restarting the apparatus is undesirably delayed. This delay includes not only the time required for opening and closing the door, but also warm-up time.